Christchurch suburbs turn liquid

A number of Christchurch residents want their neighbourhood to be condemned as liquefaction following Friday's earthquake forced another clean-up.

Aftershocks continued to rock Christchurch on Saturday after quakes measuring 5.8 and 6.0 shook the nerves of many residents on Friday.

The quakes cut power to about 26,000 homes and caused issues with water supply and wastewater, though most of those services were back to normal by late Saturday.

But cleaning up huge amounts of silt caused by liquefaction was the biggest problem for many residents in the suburb of Parklands, who have already faced this issue twice before.

Soil liquefaction describes a phenomenon whereby a saturated soil substantially loses strength and stiffness in response to applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.

"We've had enough. We can't keep doing this. This will happen again and again," resident Geoff Cooke told One News.

The area was zoned orange at one point but later switched back to green, or inhabitable. But with further liquefaction, they called for it to be rezoned red, or uninhabitable.

Prime Minister John Key said a reassessment may be necessary.

"It's possible that some of those boundaries might change and go into red, but we'll need to take a closer look at that when we can properly assess it, which will probably be early in the new year."

Mr Key told media in Auckland on Saturday that he didn't expect the latest quakes would impact on the bill forecast by Treasury to be between $NZ20 billion ($A15.38 billion) and $NZ30 billion ($A23.07 billion).

"We'll have to go and do a full assessment later on but it's likely that most of the damage has taken place in areas that are already damaged."

Electronic transactions operator Paymark said transactions in Christchurch were down 17.5 per cent on Friday compared to the same day last year in the wake of many mall closures, though there was a significant increase on Saturday as shoppers tried to catch up.

The number of homes without power was down to about 50 on Saturday afternoon and Christchurch Mayor Bob Parker hoped most of the emergency repairs could be finished on Saturday.

"It has been a hellish year. I am determined to get as much as we can fixed by tonight so that our staff, apart from a skeleton team, can spend Christmas with their families."